Impacts of hydrous manganese oxide on the retention and lability of dissolved organic matter
Abstract Minerals constitute a primary ecosystem control on organic C decomposition in soils, and therefore on greenhouse gas fluxes to the atmosphere. Secondary minerals, in particular, Fe and Al (oxyhydr)oxides—collectively referred to as “oxides” hereafter—are prominent protectors of organic C ag...
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| Format: | Article |
| Language: | English |
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BMC
2018-02-01
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| Series: | Geochemical Transactions |
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| Online Access: | http://link.springer.com/article/10.1186/s12932-018-0051-x |
| _version_ | 1818449503241371648 |
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| author | Jason W. Stuckey Christopher Goodwin Jian Wang Louis A. Kaplan Prian Vidal-Esquivel Thomas P. Beebe Donald L. Sparks |
| author_facet | Jason W. Stuckey Christopher Goodwin Jian Wang Louis A. Kaplan Prian Vidal-Esquivel Thomas P. Beebe Donald L. Sparks |
| author_sort | Jason W. Stuckey |
| collection | DOAJ |
| description | Abstract Minerals constitute a primary ecosystem control on organic C decomposition in soils, and therefore on greenhouse gas fluxes to the atmosphere. Secondary minerals, in particular, Fe and Al (oxyhydr)oxides—collectively referred to as “oxides” hereafter—are prominent protectors of organic C against microbial decomposition through sorption and complexation reactions. However, the impacts of Mn oxides on organic C retention and lability in soils are poorly understood. Here we show that hydrous Mn oxide (HMO), a poorly crystalline δ-MnO2, has a greater maximum sorption capacity for dissolved organic matter (DOM) derived from a deciduous forest composite Oi, Oe, and Oa horizon leachate (“O horizon leachate” hereafter) than does goethite under acidic (pH 5) conditions. Nonetheless, goethite has a stronger sorption capacity for DOM at low initial C:(Mn or Fe) molar ratios compared to HMO, probably due to ligand exchange with carboxylate groups as revealed by attenuated total reflectance-Fourier transform infrared spectroscopy. X-ray photoelectron spectroscopy and scanning transmission X-ray microscopy–near-edge X-ray absorption fine structure spectroscopy coupled with Mn mass balance calculations reveal that DOM sorption onto HMO induces partial Mn reductive dissolution and Mn reduction of the residual HMO. X-ray photoelectron spectroscopy further shows increasing Mn(II) concentrations are correlated with increasing oxidized C (C=O) content (r = 0.78, P < 0.0006) on the DOM–HMO complexes. We posit that DOM is the more probable reductant of HMO, as Mn(II)-induced HMO dissolution does not alter the Mn speciation of the residual HMO at pH 5. At a lower C loading (2 × 102 μg C m−2), DOM desorption—assessed by 0.1 M NaH2PO4 extraction—is lower for HMO than for goethite, whereas the extent of desorption is the same at a higher C loading (4 × 102 μg C m−2). No significant differences are observed in the impacts of HMO and goethite on the biodegradability of the DOM remaining in solution after DOM sorption reaches steady state. Overall, HMO shows a relatively strong capacity to sorb DOM and resist phosphate-induced desorption, but DOM–HMO complexes may be more vulnerable to reductive dissolution than DOM–goethite complexes. |
| first_indexed | 2024-12-14T20:36:26Z |
| format | Article |
| id | doaj.art-993d95e70506479faef934435cc3018b |
| institution | Directory Open Access Journal |
| issn | 1467-4866 |
| language | English |
| last_indexed | 2024-12-14T20:36:26Z |
| publishDate | 2018-02-01 |
| publisher | BMC |
| record_format | Article |
| series | Geochemical Transactions |
| spelling | doaj.art-993d95e70506479faef934435cc3018b2022-12-21T22:48:23ZengBMCGeochemical Transactions1467-48662018-02-0119111910.1186/s12932-018-0051-xImpacts of hydrous manganese oxide on the retention and lability of dissolved organic matterJason W. Stuckey0Christopher Goodwin1Jian Wang2Louis A. Kaplan3Prian Vidal-Esquivel4Thomas P. Beebe5Donald L. Sparks6Biology Department, Multnomah UniversityDepartment of Chemistry and Biochemistry, University of DelawareCanadian Light Source Inc., University of SaskatchewanStroud Water Research CenterDepartment of Plant & Soil Sciences and Delaware Environmental Institute, University of DelawareDepartment of Chemistry and Biochemistry, University of DelawareDepartment of Plant & Soil Sciences and Delaware Environmental Institute, University of DelawareAbstract Minerals constitute a primary ecosystem control on organic C decomposition in soils, and therefore on greenhouse gas fluxes to the atmosphere. Secondary minerals, in particular, Fe and Al (oxyhydr)oxides—collectively referred to as “oxides” hereafter—are prominent protectors of organic C against microbial decomposition through sorption and complexation reactions. However, the impacts of Mn oxides on organic C retention and lability in soils are poorly understood. Here we show that hydrous Mn oxide (HMO), a poorly crystalline δ-MnO2, has a greater maximum sorption capacity for dissolved organic matter (DOM) derived from a deciduous forest composite Oi, Oe, and Oa horizon leachate (“O horizon leachate” hereafter) than does goethite under acidic (pH 5) conditions. Nonetheless, goethite has a stronger sorption capacity for DOM at low initial C:(Mn or Fe) molar ratios compared to HMO, probably due to ligand exchange with carboxylate groups as revealed by attenuated total reflectance-Fourier transform infrared spectroscopy. X-ray photoelectron spectroscopy and scanning transmission X-ray microscopy–near-edge X-ray absorption fine structure spectroscopy coupled with Mn mass balance calculations reveal that DOM sorption onto HMO induces partial Mn reductive dissolution and Mn reduction of the residual HMO. X-ray photoelectron spectroscopy further shows increasing Mn(II) concentrations are correlated with increasing oxidized C (C=O) content (r = 0.78, P < 0.0006) on the DOM–HMO complexes. We posit that DOM is the more probable reductant of HMO, as Mn(II)-induced HMO dissolution does not alter the Mn speciation of the residual HMO at pH 5. At a lower C loading (2 × 102 μg C m−2), DOM desorption—assessed by 0.1 M NaH2PO4 extraction—is lower for HMO than for goethite, whereas the extent of desorption is the same at a higher C loading (4 × 102 μg C m−2). No significant differences are observed in the impacts of HMO and goethite on the biodegradability of the DOM remaining in solution after DOM sorption reaches steady state. Overall, HMO shows a relatively strong capacity to sorb DOM and resist phosphate-induced desorption, but DOM–HMO complexes may be more vulnerable to reductive dissolution than DOM–goethite complexes.http://link.springer.com/article/10.1186/s12932-018-0051-xSoil carbonDissolved organic matterManganese oxideGoethiteOrgano-mineral associations |
| spellingShingle | Jason W. Stuckey Christopher Goodwin Jian Wang Louis A. Kaplan Prian Vidal-Esquivel Thomas P. Beebe Donald L. Sparks Impacts of hydrous manganese oxide on the retention and lability of dissolved organic matter Geochemical Transactions Soil carbon Dissolved organic matter Manganese oxide Goethite Organo-mineral associations |
| title | Impacts of hydrous manganese oxide on the retention and lability of dissolved organic matter |
| title_full | Impacts of hydrous manganese oxide on the retention and lability of dissolved organic matter |
| title_fullStr | Impacts of hydrous manganese oxide on the retention and lability of dissolved organic matter |
| title_full_unstemmed | Impacts of hydrous manganese oxide on the retention and lability of dissolved organic matter |
| title_short | Impacts of hydrous manganese oxide on the retention and lability of dissolved organic matter |
| title_sort | impacts of hydrous manganese oxide on the retention and lability of dissolved organic matter |
| topic | Soil carbon Dissolved organic matter Manganese oxide Goethite Organo-mineral associations |
| url | http://link.springer.com/article/10.1186/s12932-018-0051-x |
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